I'm Aware That I'm Rare: the phaware® podcast

A new podcast series devoted to raising global pulmonary hypertension awareness with dynamic stories from PH patients, caregivers and medical professionals from around the world. New Episodes every Monday & Thursday!

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In this episode, Dr. Uyen Truong discusses how MRI has the
potential of providing as much if not more information about the
cardiovascular system as cardiac catheterization, and this may
shift the paradigm of pediatric PH care towards a safer,
noninvasive monitoring modality and significantly improve quality
of life in children with PH.

My name is Uyen Truong. I'm an associate professor at the
University of Colorado. We are affiliated with the Children's
Hospital of Colorado. I'm in the division of pediatric cardiology,
and my specialty is non-invasive imaging in cardiovascular
medicine, so echocardiography and MRI.

Because we are located where we are at altitude, we are a huge
referral center for pediatric pulmonary hypertension. Children come
from all over the country to come and be cared for at our center. A
lot of our research is based on this particular population, and so
my research of interest is trying to understand how far
non-invasive imaging can go in terms of diagnosing, screening and
managing children with pulmonary hypertension.

As of now, the conventional management is to take these kids to
cardiac catheterization, evaluate their hemodynamic status
including pulmonary vascular resistance and the pressures in their
pulmonary vasculature. But as you can imagine, this would require
putting kids under general anesthesia, which is very dangerous in
this population anyways. Some of these kids don't survive past just
being placed under anesthesia, and then to go on and place
catheters in their heart, extremely dangerous for them.

So, what I'm trying to prove is that I can get all that
information based on MRI. And if I can do that, it would open up a
world of research for us to do in terms of how these kids respond
to certain medications and what not.

The information that a cardiac catheterization can give a
clinician who's taking care of a patient with pulmonary
hypertension include anatomy of the cardiovascular system,
pressures throughout the myocardium and the vasculature as well as
something that we call acute vascular reactivity, meaning if you
give them a vasodilatory medication, such as iNO, how would their
heart respond? So I am addressing all of those points.

So first and foremost, MRI is better than catheterization in
determining cardiovascular structure. We can give contrast and
light up the entire system, and you can look into details in three
dimension as to the size. If there's any kind of stenosis, any kind
of obstruction, we would be better able to visualize that.

In terms of pressure, we are trying to show that novel
parameters that you can derive by MRI can predict pressures in the
pulmonary vasculature, and then we are also starting very recently
to perform the acute vascular reactivity in the MRI scanner itself.
So replicating what they're doing in the catheterization lab by
giving these patients inhaled nitric oxide and oxygen and then
repeating the MRI scan and seeing what happens to the
cardiovascular system.

So we just received a huge NIH grant to fund our study over five
years, and since that time, we've recruited six patients to undergo
MRI within 48 hours of a clinically indicated right-heart
catheterization. Therefore, we would hope to compare the two
methodologies within a very short period of time. And what we have
found so far is that A, we can do it. It's feasible. No one has
ever shown that you can do acute vasoreactivity similar to this in
the MRI scanner. And B, we're starting to see that there are
significant physiology changes under nitric oxide that was never
shown before. What does that mean? We're not sure yet, but we're
hoping over the long term to recruit 40 patients during that entire
five years. And that would give us enough power to do statistical
analysis and really understand what's happening.

Our inclusion criteria are children seven to 21. We chose seven
because we do not want to sedate these children. They must be
awake, which is one of the advantages of MRI, that you can do this
type of testing without having to anesthetize them, unlike
catheterization, where you have to anesthetize all of them.

We're choosing kids who have been diagnosed by right-heart
catheterization, so their mean pulmonary artery pressure has to be
above 25 millimeter mercury with a normal wedge pressure and
elevated PVR. We're excluding kids who have significant
intervention in their pulmonary vasculature because we really want
to understand the native pulmonary arterial response to iNO, rather
than a fibrotic or scarred down area of the pulmonary
vasculature.

So how I envision it is if I can prove that MRI can give
equivalent, if not superior data than right-heart catheterization,
we can use it as an endpoint for any type of pediatric research
because as of now, we don't have a reliable endpoint for pediatric
research. So we can do things like test medications, see what their
response is. As of now, there's only one FDA-approved medication
for children.

Our overall goal for what we're doing is trying to improve the
lives of children with pulmonary hypertension. As it stands, their
medical care requires serial examination of their cardio-vascular
system, which means that they are exposed to serial cardiac
catheterizations.

So if you were to say that the risk of catastrophic events such
as death or the necessity to resuscitate is about 3.3% for each
catheterization procedure, you can imagine over the lifetime of a
child how much more risky those procedures become. And so, we are
hoping to improve the lives of these children and provide something
safer, non-invasive and perhaps more accurate assessment of their
heart and vasculature.

About the Podcast

A new podcast series devoted to raising global pulmonary hypertension awareness with dynamic stories from PH patients, caregivers and medical professionals from around the world. New Episodes every Monday & Thursday.
Through this series of impactful, insightful and, most importantly, hopeful stories from members of the global pulmonary hypertension community, we hope to further the global #phaware conversation as well as to capture, engage and enable misdiagnosed and undiagnosed PH patients because early diagnosis and treatment can mean the difference between life and death.
Topics range from the importance of early diagnosis and global PH awareness, to the impact of clinical trials to how patient support and advocacy are paramount to battling this disease.
Learn more about PH at www.phaware.global